Mice will be immunized with purified monoclonal human immunoglobulin, derived from the peripheral blood of patients with monoclonal gammopathies or from the hybridization of human lymphoma/leukemia cells to murine myeloma cell lines to produce a hybridoma that secretes the human immunoglobulin found in the surface membrane of the leukemia/lymphoma cells. Mice will be immunized with this purified human immunoglobulin and their spleens removed and fused to the murine myeloma cell line P3X63AG8-653. Growing hybridomas will be tested for binding by radioimmunoassay to the particular patient's purified immunoglobulin and a panel of human immunoglobulins. Monoclonal antibodies reacting with only the immunoglobulin from the patient's tumor cells are anti-idiotypic. Monoclonal antiidiotype producing hybridomas will then be grown in the peritoneal cavity of BALB/c mice to produce high titer antibody. This antibody will be precipitated with sodium sulfate twice and dialyzed against normal saline for subsequent use in clinical trials.